Commit | Line | Data |
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85c8721f | 1 | /* audit.c -- Auditing support |
1da177e4 LT |
2 | * Gateway between the kernel (e.g., selinux) and the user-space audit daemon. |
3 | * System-call specific features have moved to auditsc.c | |
4 | * | |
5 | * Copyright 2003-2004 Red Hat Inc., Durham, North Carolina. | |
6 | * All Rights Reserved. | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or modify | |
9 | * it under the terms of the GNU General Public License as published by | |
10 | * the Free Software Foundation; either version 2 of the License, or | |
11 | * (at your option) any later version. | |
12 | * | |
13 | * This program is distributed in the hope that it will be useful, | |
14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | * GNU General Public License for more details. | |
17 | * | |
18 | * You should have received a copy of the GNU General Public License | |
19 | * along with this program; if not, write to the Free Software | |
20 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
21 | * | |
22 | * Written by Rickard E. (Rik) Faith <faith@redhat.com> | |
23 | * | |
24 | * Goals: 1) Integrate fully with SELinux. | |
25 | * 2) Minimal run-time overhead: | |
26 | * a) Minimal when syscall auditing is disabled (audit_enable=0). | |
27 | * b) Small when syscall auditing is enabled and no audit record | |
28 | * is generated (defer as much work as possible to record | |
29 | * generation time): | |
30 | * i) context is allocated, | |
31 | * ii) names from getname are stored without a copy, and | |
32 | * iii) inode information stored from path_lookup. | |
33 | * 3) Ability to disable syscall auditing at boot time (audit=0). | |
34 | * 4) Usable by other parts of the kernel (if audit_log* is called, | |
35 | * then a syscall record will be generated automatically for the | |
36 | * current syscall). | |
37 | * 5) Netlink interface to user-space. | |
38 | * 6) Support low-overhead kernel-based filtering to minimize the | |
39 | * information that must be passed to user-space. | |
40 | * | |
85c8721f | 41 | * Example user-space utilities: http://people.redhat.com/sgrubb/audit/ |
1da177e4 LT |
42 | */ |
43 | ||
44 | #include <linux/init.h> | |
45 | #include <asm/atomic.h> | |
46 | #include <asm/types.h> | |
47 | #include <linux/mm.h> | |
48 | #include <linux/module.h> | |
49 | ||
50 | #include <linux/audit.h> | |
51 | ||
52 | #include <net/sock.h> | |
53 | #include <linux/skbuff.h> | |
54 | #include <linux/netlink.h> | |
55 | ||
56 | /* No auditing will take place until audit_initialized != 0. | |
57 | * (Initialization happens after skb_init is called.) */ | |
58 | static int audit_initialized; | |
59 | ||
60 | /* No syscall auditing will take place unless audit_enabled != 0. */ | |
61 | int audit_enabled; | |
62 | ||
63 | /* Default state when kernel boots without any parameters. */ | |
64 | static int audit_default; | |
65 | ||
66 | /* If auditing cannot proceed, audit_failure selects what happens. */ | |
67 | static int audit_failure = AUDIT_FAIL_PRINTK; | |
68 | ||
69 | /* If audit records are to be written to the netlink socket, audit_pid | |
70 | * contains the (non-zero) pid. */ | |
c2f0c7c3 | 71 | int audit_pid; |
1da177e4 LT |
72 | |
73 | /* If audit_limit is non-zero, limit the rate of sending audit records | |
74 | * to that number per second. This prevents DoS attacks, but results in | |
75 | * audit records being dropped. */ | |
76 | static int audit_rate_limit; | |
77 | ||
78 | /* Number of outstanding audit_buffers allowed. */ | |
79 | static int audit_backlog_limit = 64; | |
80 | static atomic_t audit_backlog = ATOMIC_INIT(0); | |
81 | ||
c2f0c7c3 SG |
82 | /* The identity of the user shutting down the audit system. */ |
83 | uid_t audit_sig_uid = -1; | |
84 | pid_t audit_sig_pid = -1; | |
85 | ||
1da177e4 LT |
86 | /* Records can be lost in several ways: |
87 | 0) [suppressed in audit_alloc] | |
88 | 1) out of memory in audit_log_start [kmalloc of struct audit_buffer] | |
89 | 2) out of memory in audit_log_move [alloc_skb] | |
90 | 3) suppressed due to audit_rate_limit | |
91 | 4) suppressed due to audit_backlog_limit | |
92 | */ | |
93 | static atomic_t audit_lost = ATOMIC_INIT(0); | |
94 | ||
95 | /* The netlink socket. */ | |
96 | static struct sock *audit_sock; | |
97 | ||
98 | /* There are two lists of audit buffers. The txlist contains audit | |
99 | * buffers that cannot be sent immediately to the netlink device because | |
100 | * we are in an irq context (these are sent later in a tasklet). | |
101 | * | |
102 | * The second list is a list of pre-allocated audit buffers (if more | |
103 | * than AUDIT_MAXFREE are in use, the audit buffer is freed instead of | |
104 | * being placed on the freelist). */ | |
105 | static DEFINE_SPINLOCK(audit_txlist_lock); | |
106 | static DEFINE_SPINLOCK(audit_freelist_lock); | |
107 | static int audit_freelist_count = 0; | |
108 | static LIST_HEAD(audit_txlist); | |
109 | static LIST_HEAD(audit_freelist); | |
110 | ||
111 | /* There are three lists of rules -- one to search at task creation | |
112 | * time, one to search at syscall entry time, and another to search at | |
113 | * syscall exit time. */ | |
114 | static LIST_HEAD(audit_tsklist); | |
115 | static LIST_HEAD(audit_entlist); | |
116 | static LIST_HEAD(audit_extlist); | |
117 | ||
118 | /* The netlink socket is only to be read by 1 CPU, which lets us assume | |
119 | * that list additions and deletions never happen simultaneiously in | |
120 | * auditsc.c */ | |
121 | static DECLARE_MUTEX(audit_netlink_sem); | |
122 | ||
123 | /* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting | |
124 | * audit records. Since printk uses a 1024 byte buffer, this buffer | |
125 | * should be at least that large. */ | |
126 | #define AUDIT_BUFSIZ 1024 | |
127 | ||
128 | /* AUDIT_MAXFREE is the number of empty audit_buffers we keep on the | |
129 | * audit_freelist. Doing so eliminates many kmalloc/kfree calls. */ | |
130 | #define AUDIT_MAXFREE (2*NR_CPUS) | |
131 | ||
132 | /* The audit_buffer is used when formatting an audit record. The caller | |
133 | * locks briefly to get the record off the freelist or to allocate the | |
134 | * buffer, and locks briefly to send the buffer to the netlink layer or | |
135 | * to place it on a transmit queue. Multiple audit_buffers can be in | |
136 | * use simultaneously. */ | |
137 | struct audit_buffer { | |
138 | struct list_head list; | |
8fc6115c | 139 | struct sk_buff *skb; /* formatted skb ready to send */ |
1da177e4 LT |
140 | struct audit_context *ctx; /* NULL or associated context */ |
141 | int len; /* used area of tmp */ | |
8fc6115c CW |
142 | int size; /* size of tmp */ |
143 | char *tmp; | |
1da177e4 LT |
144 | int type; |
145 | int pid; | |
1da177e4 LT |
146 | }; |
147 | ||
148 | void audit_set_type(struct audit_buffer *ab, int type) | |
149 | { | |
150 | ab->type = type; | |
151 | } | |
152 | ||
153 | struct audit_entry { | |
154 | struct list_head list; | |
155 | struct audit_rule rule; | |
156 | }; | |
157 | ||
158 | static void audit_log_end_irq(struct audit_buffer *ab); | |
159 | static void audit_log_end_fast(struct audit_buffer *ab); | |
160 | ||
161 | static void audit_panic(const char *message) | |
162 | { | |
163 | switch (audit_failure) | |
164 | { | |
165 | case AUDIT_FAIL_SILENT: | |
166 | break; | |
167 | case AUDIT_FAIL_PRINTK: | |
168 | printk(KERN_ERR "audit: %s\n", message); | |
169 | break; | |
170 | case AUDIT_FAIL_PANIC: | |
171 | panic("audit: %s\n", message); | |
172 | break; | |
173 | } | |
174 | } | |
175 | ||
176 | static inline int audit_rate_check(void) | |
177 | { | |
178 | static unsigned long last_check = 0; | |
179 | static int messages = 0; | |
180 | static DEFINE_SPINLOCK(lock); | |
181 | unsigned long flags; | |
182 | unsigned long now; | |
183 | unsigned long elapsed; | |
184 | int retval = 0; | |
185 | ||
186 | if (!audit_rate_limit) return 1; | |
187 | ||
188 | spin_lock_irqsave(&lock, flags); | |
189 | if (++messages < audit_rate_limit) { | |
190 | retval = 1; | |
191 | } else { | |
192 | now = jiffies; | |
193 | elapsed = now - last_check; | |
194 | if (elapsed > HZ) { | |
195 | last_check = now; | |
196 | messages = 0; | |
197 | retval = 1; | |
198 | } | |
199 | } | |
200 | spin_unlock_irqrestore(&lock, flags); | |
201 | ||
202 | return retval; | |
203 | } | |
204 | ||
205 | /* Emit at least 1 message per second, even if audit_rate_check is | |
206 | * throttling. */ | |
207 | void audit_log_lost(const char *message) | |
208 | { | |
209 | static unsigned long last_msg = 0; | |
210 | static DEFINE_SPINLOCK(lock); | |
211 | unsigned long flags; | |
212 | unsigned long now; | |
213 | int print; | |
214 | ||
215 | atomic_inc(&audit_lost); | |
216 | ||
217 | print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit); | |
218 | ||
219 | if (!print) { | |
220 | spin_lock_irqsave(&lock, flags); | |
221 | now = jiffies; | |
222 | if (now - last_msg > HZ) { | |
223 | print = 1; | |
224 | last_msg = now; | |
225 | } | |
226 | spin_unlock_irqrestore(&lock, flags); | |
227 | } | |
228 | ||
229 | if (print) { | |
230 | printk(KERN_WARNING | |
231 | "audit: audit_lost=%d audit_backlog=%d" | |
232 | " audit_rate_limit=%d audit_backlog_limit=%d\n", | |
233 | atomic_read(&audit_lost), | |
234 | atomic_read(&audit_backlog), | |
235 | audit_rate_limit, | |
236 | audit_backlog_limit); | |
237 | audit_panic(message); | |
238 | } | |
239 | ||
240 | } | |
241 | ||
c94c257c | 242 | static int audit_set_rate_limit(int limit, uid_t loginuid) |
1da177e4 LT |
243 | { |
244 | int old = audit_rate_limit; | |
245 | audit_rate_limit = limit; | |
c94c257c SH |
246 | audit_log(NULL, "audit_rate_limit=%d old=%d by auid %u", |
247 | audit_rate_limit, old, loginuid); | |
1da177e4 LT |
248 | return old; |
249 | } | |
250 | ||
c94c257c | 251 | static int audit_set_backlog_limit(int limit, uid_t loginuid) |
1da177e4 LT |
252 | { |
253 | int old = audit_backlog_limit; | |
254 | audit_backlog_limit = limit; | |
c94c257c SH |
255 | audit_log(NULL, "audit_backlog_limit=%d old=%d by auid %u", |
256 | audit_backlog_limit, old, loginuid); | |
1da177e4 LT |
257 | return old; |
258 | } | |
259 | ||
c94c257c | 260 | static int audit_set_enabled(int state, uid_t loginuid) |
1da177e4 LT |
261 | { |
262 | int old = audit_enabled; | |
263 | if (state != 0 && state != 1) | |
264 | return -EINVAL; | |
265 | audit_enabled = state; | |
c94c257c SH |
266 | audit_log(NULL, "audit_enabled=%d old=%d by auid %u", |
267 | audit_enabled, old, loginuid); | |
1da177e4 LT |
268 | return old; |
269 | } | |
270 | ||
c94c257c | 271 | static int audit_set_failure(int state, uid_t loginuid) |
1da177e4 LT |
272 | { |
273 | int old = audit_failure; | |
274 | if (state != AUDIT_FAIL_SILENT | |
275 | && state != AUDIT_FAIL_PRINTK | |
276 | && state != AUDIT_FAIL_PANIC) | |
277 | return -EINVAL; | |
278 | audit_failure = state; | |
c94c257c SH |
279 | audit_log(NULL, "audit_failure=%d old=%d by auid %u", |
280 | audit_failure, old, loginuid); | |
1da177e4 LT |
281 | return old; |
282 | } | |
283 | ||
284 | #ifdef CONFIG_NET | |
285 | void audit_send_reply(int pid, int seq, int type, int done, int multi, | |
286 | void *payload, int size) | |
287 | { | |
288 | struct sk_buff *skb; | |
289 | struct nlmsghdr *nlh; | |
290 | int len = NLMSG_SPACE(size); | |
291 | void *data; | |
292 | int flags = multi ? NLM_F_MULTI : 0; | |
293 | int t = done ? NLMSG_DONE : type; | |
294 | ||
295 | skb = alloc_skb(len, GFP_KERNEL); | |
296 | if (!skb) | |
297 | goto nlmsg_failure; | |
298 | ||
299 | nlh = NLMSG_PUT(skb, pid, seq, t, len - sizeof(*nlh)); | |
300 | nlh->nlmsg_flags = flags; | |
301 | data = NLMSG_DATA(nlh); | |
302 | memcpy(data, payload, size); | |
303 | netlink_unicast(audit_sock, skb, pid, MSG_DONTWAIT); | |
304 | return; | |
305 | ||
306 | nlmsg_failure: /* Used by NLMSG_PUT */ | |
307 | if (skb) | |
308 | kfree_skb(skb); | |
309 | } | |
310 | ||
311 | /* | |
312 | * Check for appropriate CAP_AUDIT_ capabilities on incoming audit | |
313 | * control messages. | |
314 | */ | |
315 | static int audit_netlink_ok(kernel_cap_t eff_cap, u16 msg_type) | |
316 | { | |
317 | int err = 0; | |
318 | ||
319 | switch (msg_type) { | |
320 | case AUDIT_GET: | |
321 | case AUDIT_LIST: | |
322 | case AUDIT_SET: | |
323 | case AUDIT_ADD: | |
324 | case AUDIT_DEL: | |
c2f0c7c3 | 325 | case AUDIT_SIGNAL_INFO: |
1da177e4 LT |
326 | if (!cap_raised(eff_cap, CAP_AUDIT_CONTROL)) |
327 | err = -EPERM; | |
328 | break; | |
329 | case AUDIT_USER: | |
330 | if (!cap_raised(eff_cap, CAP_AUDIT_WRITE)) | |
331 | err = -EPERM; | |
332 | break; | |
333 | default: /* bad msg */ | |
334 | err = -EINVAL; | |
335 | } | |
336 | ||
337 | return err; | |
338 | } | |
339 | ||
340 | static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) | |
341 | { | |
342 | u32 uid, pid, seq; | |
343 | void *data; | |
344 | struct audit_status *status_get, status_set; | |
345 | int err; | |
346 | struct audit_buffer *ab; | |
347 | u16 msg_type = nlh->nlmsg_type; | |
c94c257c | 348 | uid_t loginuid; /* loginuid of sender */ |
c2f0c7c3 | 349 | struct audit_sig_info sig_data; |
1da177e4 LT |
350 | |
351 | err = audit_netlink_ok(NETLINK_CB(skb).eff_cap, msg_type); | |
352 | if (err) | |
353 | return err; | |
354 | ||
355 | pid = NETLINK_CREDS(skb)->pid; | |
356 | uid = NETLINK_CREDS(skb)->uid; | |
c94c257c | 357 | loginuid = NETLINK_CB(skb).loginuid; |
1da177e4 LT |
358 | seq = nlh->nlmsg_seq; |
359 | data = NLMSG_DATA(nlh); | |
360 | ||
361 | switch (msg_type) { | |
362 | case AUDIT_GET: | |
363 | status_set.enabled = audit_enabled; | |
364 | status_set.failure = audit_failure; | |
365 | status_set.pid = audit_pid; | |
366 | status_set.rate_limit = audit_rate_limit; | |
367 | status_set.backlog_limit = audit_backlog_limit; | |
368 | status_set.lost = atomic_read(&audit_lost); | |
369 | status_set.backlog = atomic_read(&audit_backlog); | |
370 | audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_GET, 0, 0, | |
371 | &status_set, sizeof(status_set)); | |
372 | break; | |
373 | case AUDIT_SET: | |
374 | if (nlh->nlmsg_len < sizeof(struct audit_status)) | |
375 | return -EINVAL; | |
376 | status_get = (struct audit_status *)data; | |
377 | if (status_get->mask & AUDIT_STATUS_ENABLED) { | |
c94c257c | 378 | err = audit_set_enabled(status_get->enabled, loginuid); |
1da177e4 LT |
379 | if (err < 0) return err; |
380 | } | |
381 | if (status_get->mask & AUDIT_STATUS_FAILURE) { | |
c94c257c | 382 | err = audit_set_failure(status_get->failure, loginuid); |
1da177e4 LT |
383 | if (err < 0) return err; |
384 | } | |
385 | if (status_get->mask & AUDIT_STATUS_PID) { | |
386 | int old = audit_pid; | |
387 | audit_pid = status_get->pid; | |
c94c257c SH |
388 | audit_log(NULL, "audit_pid=%d old=%d by auid %u", |
389 | audit_pid, old, loginuid); | |
1da177e4 LT |
390 | } |
391 | if (status_get->mask & AUDIT_STATUS_RATE_LIMIT) | |
c94c257c | 392 | audit_set_rate_limit(status_get->rate_limit, loginuid); |
1da177e4 | 393 | if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT) |
c94c257c SH |
394 | audit_set_backlog_limit(status_get->backlog_limit, |
395 | loginuid); | |
1da177e4 LT |
396 | break; |
397 | case AUDIT_USER: | |
398 | ab = audit_log_start(NULL); | |
399 | if (!ab) | |
400 | break; /* audit_panic has been called */ | |
401 | audit_log_format(ab, | |
c94c257c SH |
402 | "user pid=%d uid=%d length=%d loginuid=%u" |
403 | " msg='%.1024s'", | |
1da177e4 LT |
404 | pid, uid, |
405 | (int)(nlh->nlmsg_len | |
406 | - ((char *)data - (char *)nlh)), | |
c94c257c | 407 | loginuid, (char *)data); |
1da177e4 LT |
408 | ab->type = AUDIT_USER; |
409 | ab->pid = pid; | |
410 | audit_log_end(ab); | |
411 | break; | |
412 | case AUDIT_ADD: | |
413 | case AUDIT_DEL: | |
414 | if (nlh->nlmsg_len < sizeof(struct audit_rule)) | |
415 | return -EINVAL; | |
416 | /* fallthrough */ | |
417 | case AUDIT_LIST: | |
418 | #ifdef CONFIG_AUDITSYSCALL | |
419 | err = audit_receive_filter(nlh->nlmsg_type, NETLINK_CB(skb).pid, | |
c94c257c | 420 | uid, seq, data, loginuid); |
1da177e4 LT |
421 | #else |
422 | err = -EOPNOTSUPP; | |
423 | #endif | |
424 | break; | |
c2f0c7c3 SG |
425 | case AUDIT_SIGNAL_INFO: |
426 | sig_data.uid = audit_sig_uid; | |
427 | sig_data.pid = audit_sig_pid; | |
428 | audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_SIGNAL_INFO, | |
429 | 0, 0, &sig_data, sizeof(sig_data)); | |
430 | break; | |
1da177e4 LT |
431 | default: |
432 | err = -EINVAL; | |
433 | break; | |
434 | } | |
435 | ||
436 | return err < 0 ? err : 0; | |
437 | } | |
438 | ||
439 | /* Get message from skb (based on rtnetlink_rcv_skb). Each message is | |
440 | * processed by audit_receive_msg. Malformed skbs with wrong length are | |
441 | * discarded silently. */ | |
2a0a6ebe | 442 | static void audit_receive_skb(struct sk_buff *skb) |
1da177e4 LT |
443 | { |
444 | int err; | |
445 | struct nlmsghdr *nlh; | |
446 | u32 rlen; | |
447 | ||
448 | while (skb->len >= NLMSG_SPACE(0)) { | |
449 | nlh = (struct nlmsghdr *)skb->data; | |
450 | if (nlh->nlmsg_len < sizeof(*nlh) || skb->len < nlh->nlmsg_len) | |
2a0a6ebe | 451 | return; |
1da177e4 LT |
452 | rlen = NLMSG_ALIGN(nlh->nlmsg_len); |
453 | if (rlen > skb->len) | |
454 | rlen = skb->len; | |
455 | if ((err = audit_receive_msg(skb, nlh))) { | |
456 | netlink_ack(skb, nlh, err); | |
457 | } else if (nlh->nlmsg_flags & NLM_F_ACK) | |
458 | netlink_ack(skb, nlh, 0); | |
459 | skb_pull(skb, rlen); | |
460 | } | |
1da177e4 LT |
461 | } |
462 | ||
463 | /* Receive messages from netlink socket. */ | |
464 | static void audit_receive(struct sock *sk, int length) | |
465 | { | |
466 | struct sk_buff *skb; | |
2a0a6ebe | 467 | unsigned int qlen; |
1da177e4 | 468 | |
2a0a6ebe | 469 | down(&audit_netlink_sem); |
1da177e4 | 470 | |
2a0a6ebe HX |
471 | for (qlen = skb_queue_len(&sk->sk_receive_queue); qlen; qlen--) { |
472 | skb = skb_dequeue(&sk->sk_receive_queue); | |
473 | audit_receive_skb(skb); | |
474 | kfree_skb(skb); | |
1da177e4 LT |
475 | } |
476 | up(&audit_netlink_sem); | |
477 | } | |
478 | ||
479 | /* Move data from tmp buffer into an skb. This is an extra copy, and | |
480 | * that is unfortunate. However, the copy will only occur when a record | |
481 | * is being written to user space, which is already a high-overhead | |
482 | * operation. (Elimination of the copy is possible, for example, by | |
483 | * writing directly into a pre-allocated skb, at the cost of wasting | |
484 | * memory. */ | |
485 | static void audit_log_move(struct audit_buffer *ab) | |
486 | { | |
487 | struct sk_buff *skb; | |
8fc6115c | 488 | struct nlmsghdr *nlh; |
1da177e4 | 489 | char *start; |
8fc6115c | 490 | int len = NLMSG_SPACE(0) + ab->len + 1; |
1da177e4 LT |
491 | |
492 | /* possible resubmission */ | |
8fc6115c | 493 | if (ab->skb) |
1da177e4 LT |
494 | return; |
495 | ||
8fc6115c CW |
496 | skb = alloc_skb(len, GFP_ATOMIC); |
497 | if (!skb) { | |
498 | /* Lose information in ab->tmp */ | |
499 | audit_log_lost("out of memory in audit_log_move"); | |
500 | return; | |
1da177e4 | 501 | } |
8fc6115c CW |
502 | ab->skb = skb; |
503 | nlh = (struct nlmsghdr *)skb_put(skb, NLMSG_SPACE(0)); | |
504 | nlh->nlmsg_type = ab->type; | |
505 | nlh->nlmsg_len = ab->len; | |
506 | nlh->nlmsg_flags = 0; | |
507 | nlh->nlmsg_pid = ab->pid; | |
508 | nlh->nlmsg_seq = 0; | |
1da177e4 LT |
509 | start = skb_put(skb, ab->len); |
510 | memcpy(start, ab->tmp, ab->len); | |
1da177e4 LT |
511 | } |
512 | ||
513 | /* Iterate over the skbuff in the audit_buffer, sending their contents | |
514 | * to user space. */ | |
515 | static inline int audit_log_drain(struct audit_buffer *ab) | |
516 | { | |
8fc6115c | 517 | struct sk_buff *skb = ab->skb; |
1da177e4 | 518 | |
8fc6115c | 519 | if (skb) { |
1da177e4 LT |
520 | int retval = 0; |
521 | ||
522 | if (audit_pid) { | |
1da177e4 LT |
523 | skb_get(skb); /* because netlink_* frees */ |
524 | retval = netlink_unicast(audit_sock, skb, audit_pid, | |
525 | MSG_DONTWAIT); | |
526 | } | |
37509e74 CW |
527 | if (retval == -EAGAIN && |
528 | (atomic_read(&audit_backlog)) < audit_backlog_limit) { | |
1da177e4 LT |
529 | audit_log_end_irq(ab); |
530 | return 1; | |
531 | } | |
532 | if (retval < 0) { | |
533 | if (retval == -ECONNREFUSED) { | |
534 | printk(KERN_ERR | |
535 | "audit: *NO* daemon at audit_pid=%d\n", | |
536 | audit_pid); | |
537 | audit_pid = 0; | |
538 | } else | |
539 | audit_log_lost("netlink socket too busy"); | |
540 | } | |
541 | if (!audit_pid) { /* No daemon */ | |
8fc6115c | 542 | int offset = NLMSG_SPACE(0); |
1da177e4 | 543 | int len = skb->len - offset; |
c7fcb0ee PM |
544 | skb->data[offset + len] = '\0'; |
545 | printk(KERN_ERR "%s\n", skb->data + offset); | |
1da177e4 LT |
546 | } |
547 | kfree_skb(skb); | |
1da177e4 LT |
548 | } |
549 | return 0; | |
550 | } | |
551 | ||
552 | /* Initialize audit support at boot time. */ | |
553 | static int __init audit_init(void) | |
554 | { | |
555 | printk(KERN_INFO "audit: initializing netlink socket (%s)\n", | |
556 | audit_default ? "enabled" : "disabled"); | |
557 | audit_sock = netlink_kernel_create(NETLINK_AUDIT, audit_receive); | |
558 | if (!audit_sock) | |
559 | audit_panic("cannot initialize netlink socket"); | |
560 | ||
561 | audit_initialized = 1; | |
562 | audit_enabled = audit_default; | |
563 | audit_log(NULL, "initialized"); | |
564 | return 0; | |
565 | } | |
566 | ||
567 | #else | |
568 | /* Without CONFIG_NET, we have no skbuffs. For now, print what we have | |
569 | * in the buffer. */ | |
570 | static void audit_log_move(struct audit_buffer *ab) | |
571 | { | |
572 | printk(KERN_ERR "%*.*s\n", ab->len, ab->len, ab->tmp); | |
573 | ab->len = 0; | |
574 | } | |
575 | ||
576 | static inline int audit_log_drain(struct audit_buffer *ab) | |
577 | { | |
578 | return 0; | |
579 | } | |
580 | ||
581 | /* Initialize audit support at boot time. */ | |
582 | int __init audit_init(void) | |
583 | { | |
584 | printk(KERN_INFO "audit: initializing WITHOUT netlink support\n"); | |
585 | audit_sock = NULL; | |
586 | audit_pid = 0; | |
587 | ||
588 | audit_initialized = 1; | |
589 | audit_enabled = audit_default; | |
590 | audit_log(NULL, "initialized"); | |
591 | return 0; | |
592 | } | |
593 | #endif | |
594 | ||
595 | __initcall(audit_init); | |
596 | ||
597 | /* Process kernel command-line parameter at boot time. audit=0 or audit=1. */ | |
598 | static int __init audit_enable(char *str) | |
599 | { | |
600 | audit_default = !!simple_strtol(str, NULL, 0); | |
601 | printk(KERN_INFO "audit: %s%s\n", | |
602 | audit_default ? "enabled" : "disabled", | |
603 | audit_initialized ? "" : " (after initialization)"); | |
604 | if (audit_initialized) | |
605 | audit_enabled = audit_default; | |
606 | return 0; | |
607 | } | |
608 | ||
609 | __setup("audit=", audit_enable); | |
610 | ||
16e1904e CW |
611 | static void audit_buffer_free(struct audit_buffer *ab) |
612 | { | |
613 | unsigned long flags; | |
614 | ||
8fc6115c CW |
615 | if (!ab) |
616 | return; | |
617 | ||
618 | kfree(ab->tmp); | |
16e1904e CW |
619 | atomic_dec(&audit_backlog); |
620 | spin_lock_irqsave(&audit_freelist_lock, flags); | |
621 | if (++audit_freelist_count > AUDIT_MAXFREE) | |
622 | kfree(ab); | |
623 | else | |
624 | list_add(&ab->list, &audit_freelist); | |
625 | spin_unlock_irqrestore(&audit_freelist_lock, flags); | |
626 | } | |
627 | ||
8fc6115c CW |
628 | static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx, |
629 | int gfp_mask) | |
16e1904e CW |
630 | { |
631 | unsigned long flags; | |
632 | struct audit_buffer *ab = NULL; | |
633 | ||
634 | spin_lock_irqsave(&audit_freelist_lock, flags); | |
635 | if (!list_empty(&audit_freelist)) { | |
636 | ab = list_entry(audit_freelist.next, | |
637 | struct audit_buffer, list); | |
638 | list_del(&ab->list); | |
639 | --audit_freelist_count; | |
640 | } | |
641 | spin_unlock_irqrestore(&audit_freelist_lock, flags); | |
642 | ||
643 | if (!ab) { | |
644 | ab = kmalloc(sizeof(*ab), GFP_ATOMIC); | |
645 | if (!ab) | |
8fc6115c | 646 | goto err; |
16e1904e CW |
647 | } |
648 | atomic_inc(&audit_backlog); | |
8fc6115c CW |
649 | |
650 | ab->tmp = kmalloc(AUDIT_BUFSIZ, GFP_ATOMIC); | |
651 | if (!ab->tmp) | |
652 | goto err; | |
653 | ||
654 | ab->skb = NULL; | |
655 | ab->ctx = ctx; | |
656 | ab->len = 0; | |
657 | ab->size = AUDIT_BUFSIZ; | |
658 | ab->type = AUDIT_KERNEL; | |
659 | ab->pid = 0; | |
16e1904e | 660 | return ab; |
8fc6115c CW |
661 | err: |
662 | audit_buffer_free(ab); | |
663 | return NULL; | |
16e1904e | 664 | } |
1da177e4 LT |
665 | |
666 | /* Obtain an audit buffer. This routine does locking to obtain the | |
667 | * audit buffer, but then no locking is required for calls to | |
668 | * audit_log_*format. If the tsk is a task that is currently in a | |
669 | * syscall, then the syscall is marked as auditable and an audit record | |
670 | * will be written at syscall exit. If there is no associated task, tsk | |
671 | * should be NULL. */ | |
672 | struct audit_buffer *audit_log_start(struct audit_context *ctx) | |
673 | { | |
674 | struct audit_buffer *ab = NULL; | |
1da177e4 | 675 | struct timespec t; |
d812ddbb | 676 | unsigned int serial; |
1da177e4 LT |
677 | |
678 | if (!audit_initialized) | |
679 | return NULL; | |
680 | ||
681 | if (audit_backlog_limit | |
682 | && atomic_read(&audit_backlog) > audit_backlog_limit) { | |
683 | if (audit_rate_check()) | |
684 | printk(KERN_WARNING | |
685 | "audit: audit_backlog=%d > " | |
686 | "audit_backlog_limit=%d\n", | |
687 | atomic_read(&audit_backlog), | |
688 | audit_backlog_limit); | |
689 | audit_log_lost("backlog limit exceeded"); | |
690 | return NULL; | |
691 | } | |
692 | ||
8fc6115c | 693 | ab = audit_buffer_alloc(ctx, GFP_ATOMIC); |
1da177e4 LT |
694 | if (!ab) { |
695 | audit_log_lost("out of memory in audit_log_start"); | |
696 | return NULL; | |
697 | } | |
698 | ||
1da177e4 LT |
699 | #ifdef CONFIG_AUDITSYSCALL |
700 | if (ab->ctx) | |
701 | audit_get_stamp(ab->ctx, &t, &serial); | |
702 | else | |
703 | #endif | |
d812ddbb | 704 | { |
1da177e4 | 705 | t = CURRENT_TIME; |
d812ddbb SG |
706 | serial = 0; |
707 | } | |
1da177e4 LT |
708 | audit_log_format(ab, "audit(%lu.%03lu:%u): ", |
709 | t.tv_sec, t.tv_nsec/1000000, serial); | |
710 | return ab; | |
711 | } | |
712 | ||
8fc6115c CW |
713 | /** |
714 | * audit_expand - expand tmp buffer in the audit buffer | |
715 | * @ab: audit_buffer | |
716 | * | |
717 | * Returns 0 (no space) on failed expansion, or available space if | |
718 | * successful. | |
719 | */ | |
720 | static inline int audit_expand(struct audit_buffer *ab) | |
721 | { | |
722 | char *tmp; | |
723 | int len = ab->size + AUDIT_BUFSIZ; | |
724 | ||
725 | tmp = kmalloc(len, GFP_ATOMIC); | |
726 | if (!tmp) | |
727 | return 0; | |
728 | memcpy(tmp, ab->tmp, ab->len); | |
729 | kfree(ab->tmp); | |
730 | ab->tmp = tmp; | |
731 | ab->size = len; | |
732 | return ab->size - ab->len; | |
733 | } | |
1da177e4 LT |
734 | |
735 | /* Format an audit message into the audit buffer. If there isn't enough | |
736 | * room in the audit buffer, more room will be allocated and vsnprint | |
737 | * will be called a second time. Currently, we assume that a printk | |
738 | * can't format message larger than 1024 bytes, so we don't either. */ | |
739 | static void audit_log_vformat(struct audit_buffer *ab, const char *fmt, | |
740 | va_list args) | |
741 | { | |
742 | int len, avail; | |
743 | ||
744 | if (!ab) | |
745 | return; | |
746 | ||
8fc6115c | 747 | avail = ab->size - ab->len; |
1da177e4 | 748 | if (avail <= 0) { |
8fc6115c CW |
749 | avail = audit_expand(ab); |
750 | if (!avail) | |
751 | goto out; | |
1da177e4 | 752 | } |
8fc6115c | 753 | len = vsnprintf(ab->tmp + ab->len, avail, fmt, args); |
1da177e4 LT |
754 | if (len >= avail) { |
755 | /* The printk buffer is 1024 bytes long, so if we get | |
756 | * here and AUDIT_BUFSIZ is at least 1024, then we can | |
757 | * log everything that printk could have logged. */ | |
8fc6115c CW |
758 | avail = audit_expand(ab); |
759 | if (!avail) | |
760 | goto out; | |
761 | len = vsnprintf(ab->tmp + ab->len, avail, fmt, args); | |
1da177e4 LT |
762 | } |
763 | ab->len += (len < avail) ? len : avail; | |
8fc6115c CW |
764 | out: |
765 | return; | |
1da177e4 LT |
766 | } |
767 | ||
768 | /* Format a message into the audit buffer. All the work is done in | |
769 | * audit_log_vformat. */ | |
770 | void audit_log_format(struct audit_buffer *ab, const char *fmt, ...) | |
771 | { | |
772 | va_list args; | |
773 | ||
774 | if (!ab) | |
775 | return; | |
776 | va_start(args, fmt); | |
777 | audit_log_vformat(ab, fmt, args); | |
778 | va_end(args); | |
779 | } | |
780 | ||
83c7d091 | 781 | void audit_log_hex(struct audit_buffer *ab, const unsigned char *buf, size_t len) |
782 | { | |
783 | int i; | |
784 | ||
785 | for (i=0; i<len; i++) | |
786 | audit_log_format(ab, "%02x", buf[i]); | |
787 | } | |
788 | ||
789 | void audit_log_untrustedstring(struct audit_buffer *ab, const char *string) | |
790 | { | |
81b7854d | 791 | const unsigned char *p = string; |
83c7d091 | 792 | |
793 | while (*p) { | |
794 | if (*p == '"' || *p == ' ' || *p < 0x20 || *p > 0x7f) { | |
795 | audit_log_hex(ab, string, strlen(string)); | |
796 | return; | |
797 | } | |
798 | p++; | |
799 | } | |
800 | audit_log_format(ab, "\"%s\"", string); | |
801 | } | |
802 | ||
803 | ||
1da177e4 LT |
804 | /* This is a helper-function to print the d_path without using a static |
805 | * buffer or allocating another buffer in addition to the one in | |
806 | * audit_buffer. */ | |
807 | void audit_log_d_path(struct audit_buffer *ab, const char *prefix, | |
808 | struct dentry *dentry, struct vfsmount *vfsmnt) | |
809 | { | |
810 | char *p; | |
811 | int len, avail; | |
812 | ||
8fc6115c CW |
813 | if (prefix) |
814 | audit_log_format(ab, " %s", prefix); | |
1da177e4 | 815 | |
8fc6115c | 816 | avail = ab->size - ab->len; |
1da177e4 LT |
817 | p = d_path(dentry, vfsmnt, ab->tmp + ab->len, avail); |
818 | if (IS_ERR(p)) { | |
819 | /* FIXME: can we save some information here? */ | |
820 | audit_log_format(ab, "<toolong>"); | |
821 | } else { | |
822 | /* path isn't at start of buffer */ | |
8fc6115c | 823 | len = (ab->tmp + ab->size - 1) - p; |
1da177e4 LT |
824 | memmove(ab->tmp + ab->len, p, len); |
825 | ab->len += len; | |
1da177e4 LT |
826 | } |
827 | } | |
828 | ||
829 | /* Remove queued messages from the audit_txlist and send them to userspace. */ | |
830 | static void audit_tasklet_handler(unsigned long arg) | |
831 | { | |
832 | LIST_HEAD(list); | |
833 | struct audit_buffer *ab; | |
834 | unsigned long flags; | |
835 | ||
836 | spin_lock_irqsave(&audit_txlist_lock, flags); | |
837 | list_splice_init(&audit_txlist, &list); | |
838 | spin_unlock_irqrestore(&audit_txlist_lock, flags); | |
839 | ||
840 | while (!list_empty(&list)) { | |
841 | ab = list_entry(list.next, struct audit_buffer, list); | |
842 | list_del(&ab->list); | |
843 | audit_log_end_fast(ab); | |
844 | } | |
845 | } | |
846 | ||
847 | static DECLARE_TASKLET(audit_tasklet, audit_tasklet_handler, 0); | |
848 | ||
849 | /* The netlink_* functions cannot be called inside an irq context, so | |
850 | * the audit buffer is places on a queue and a tasklet is scheduled to | |
851 | * remove them from the queue outside the irq context. May be called in | |
852 | * any context. */ | |
853 | static void audit_log_end_irq(struct audit_buffer *ab) | |
854 | { | |
855 | unsigned long flags; | |
856 | ||
857 | if (!ab) | |
858 | return; | |
859 | spin_lock_irqsave(&audit_txlist_lock, flags); | |
860 | list_add_tail(&ab->list, &audit_txlist); | |
861 | spin_unlock_irqrestore(&audit_txlist_lock, flags); | |
862 | ||
863 | tasklet_schedule(&audit_tasklet); | |
864 | } | |
865 | ||
866 | /* Send the message in the audit buffer directly to user space. May not | |
867 | * be called in an irq context. */ | |
868 | static void audit_log_end_fast(struct audit_buffer *ab) | |
869 | { | |
1da177e4 LT |
870 | BUG_ON(in_irq()); |
871 | if (!ab) | |
872 | return; | |
873 | if (!audit_rate_check()) { | |
874 | audit_log_lost("rate limit exceeded"); | |
875 | } else { | |
876 | audit_log_move(ab); | |
877 | if (audit_log_drain(ab)) | |
878 | return; | |
879 | } | |
16e1904e | 880 | audit_buffer_free(ab); |
1da177e4 LT |
881 | } |
882 | ||
883 | /* Send or queue the message in the audit buffer, depending on the | |
884 | * current context. (A convenience function that may be called in any | |
885 | * context.) */ | |
886 | void audit_log_end(struct audit_buffer *ab) | |
887 | { | |
888 | if (in_irq()) | |
889 | audit_log_end_irq(ab); | |
890 | else | |
891 | audit_log_end_fast(ab); | |
892 | } | |
893 | ||
894 | /* Log an audit record. This is a convenience function that calls | |
895 | * audit_log_start, audit_log_vformat, and audit_log_end. It may be | |
896 | * called in any context. */ | |
897 | void audit_log(struct audit_context *ctx, const char *fmt, ...) | |
898 | { | |
899 | struct audit_buffer *ab; | |
900 | va_list args; | |
901 | ||
902 | ab = audit_log_start(ctx); | |
903 | if (ab) { | |
904 | va_start(args, fmt); | |
905 | audit_log_vformat(ab, fmt, args); | |
906 | va_end(args); | |
907 | audit_log_end(ab); | |
908 | } | |
909 | } |